(1) Field of the Invention
The present invention relates to a positional information storage system that stores pieces of positional information of a communication terminal apparatus carried by a user and relates to a semiconductor memory.
(2) Description of the Related Art
In recent years, various systems that use positional information of a mobile wireless terminal have been proposed in which the positional information is acquired through a communication between the mobile wireless terminal and a base station or by using the Global Positioning System (GPS). Refer to, for example, Japanese Laid-Open Patent Application No. 2002-27527.
One of such systems is a management system for managing the working state of workers.
Here, the management system will be explained using a case where the system is used by a home delivery company.
A manager of the home delivery company needs to keep track of a worker's locations and working state while the worker delivers packages to clients outside the company building.
It is mandatory for the worker to carry a mobile wireless terminal when he/she is outside the company building.
The mobile wireless terminal acquires, every certain time period, its positional information through a communication with a base station or by using the GPS, and stores the acquired pieces of positional information in a storage area provided in itself.
The worker returns to the company building after delivering all packages assigned to the worker.
The manager in the company building can keep track of the worker's locations and working state by referring to the pieces of positional information recorded every certain time period.
However, the worker may tamper the contents of the memory or may have another person carry the mobile wireless terminal. When such unauthorized manipulations are done, the manager has wrong recognition on the worker's locations or working state.